Superchargers or Turbochargers: The Debate

General Discussion
#1

Ultimately turbos will always be better than turbochargers in most measurable ways. They are inherently more efficient and scalable. HOWEVER they are very rarely a good option on cars that weren’t turbocharged from the factory because whilst you can quantify the gains on paper the reality is that it’s way too much extra work and inevitably corners are cut in some places due to financial or practical constraints. In this case there isn’t really enough room for a perfect turbo setup.

Superchargers are just so much easier. With properly sized turbos you could, theoretically, tune an RS4 to be more powerful yet equally drivable than the supercharger alternative. It’s just that it’s not a job I would remotely want to take on. Turbocharged cars making torque mountains and slamming you in the back when they spool is just poor tuning. It’s both because of a lack of skill and the fact that it makes the car “feel” faster so you sell more tunes. When actual manufacturers build a turbo car the behavior is a LOT better. I very briefly tested a Merc-AMG GT S and you could pretty well fool most customers that it’s not actually turbocharged. It feels even bigger than the old 6.2 displacement wise. It is possible. But some bloke in a shed probably won’t manage it.

SC’d cars do sound better because the exhaust doesn’t pass through a turbine on the way out.

RS4 twin turbo kit.
RS4 twin turbo kit.
#2

Factually this isn’t true but this is what lots of people say and most think. They both have there upsides the recent dominance from the supercharged s4 b8 shows just how good the supercharged option has become.

#3

Audi has dumped the SC. Merc has dumped the SC. BMW Ms now all have turbos. Even Ferrari is going turbo, and drivability is their number one concern.

They can make more efficiently powerful engines with turbos. But that doesn’t mean everyone with a tig welder and tuner pro can do it obviously.

Let’s not pretend there are no limits to supercharger sizing. A supercharger is more limited in how much of a power multiplication factor you can achieve. If you want a supercharged 800 horsepower engine there is a certain displacement you need on the base engine. The displacement requirements of a SC for a given power target X are higher than for turbos. That’s irrefutable physics.

So it’s disingenious to call them more drivable when they operate in a much tighter window by design (limitation). You don’t see a 1000 horsepower EVO with nothing but a supercharger. You can do it with a turbo if you can put up with the lag.

None of this changes the fact that if you want more power out of a B7 RS4 specifically, a supercharger is the obvious and best choice. But in general terms, turbos are a superior way to go. Lag and boost threshold are not the issues they were 20 or even 10 years ago. Hence nearly every new car on sale today (in europe at least) having one or more turbocharger.

#4

And again your wrong. Before you post your thoughts as fact read a compressor map. Your just as bad as all the stuff people are trying to stop. You don’t even know what your talking about. I’m not saying turbos don’t have there place they each have a strong point and can in so, even aspects outshine each other in spots.

Saying lag isn’t an issue like 20 years ago is bafoonish and about as uneducated about turbos as you can be. By design the more CFM you need out of a turbo the more lag you will get that’s by design.

Each have there strong point depending on exactly what your goals are turbos or supercharged options shine.

#5

I can read compressor maps. So? The point is how you drive the compressor. That is where most of the difference lies. Superchargers spend horsepower to make horsepower. Turbos recycle otherwise lost energy.

And explain me if SCs are so awesome why manufacturers have by and large dumped them completely for turbos? Audi included.

#6

[quote=“JCviggen,post:5,topic:7207”]

did you mean consistency of you being wrong or irony that you continue to be wrong.

#7

And again your wrong. Before you post your thoughts as fact read a compressor map. Your just as bad as all the stuff people are trying to stop. You don’t even know what your talking about. I’m not saying turbos don’t have there place they each have a strong point and can in so, even aspects outshine each other in spots.

Saying lag isn’t an issue like 20 years ago is bafoonish and about as uneducated about turbos as you can be. By design the more CFM you need out of a turbo the more lag you will get that’s by design.

Each have there strong point depending on exactly what your goals are turbos or supercharged options shine.

#8

Making a howler of a grammatical error in the process of saying someone is wrong counts as ironic I would say.

You’ve not brought up a single thing that actually backs up your claims either. Simply saying I’m wrong is a bit too easy.

Again, why do you think all the big manufacturers are using turbos, turbos, turbos? There have been HUGE improvements in turbo technology from variable vane angles to the materials used. They are way less laggy than they once were in properly sized applications. That lag is worse in cases where they are boosting an engine way beyond what any supercharger could do is a given and not a relative downside.

That you even bring up compressor maps shows your technical ignorance on this subject. They are about the least relevant part of the equation here. The actual difference is about parasitic losses and energy recovery.

#9

Hey you can fix stupid and you just keep being a bag full. So you just keep posting. Learn to read a compressor map. Educate your self and try again. I realize you have a low understanding of these things and that makes sense you can just read your posts. Take some time and learn.

Superchargers were such a bad idea audi put them on more models then ever in there line up. So have other company’s.

Once again. Turbos are great and they offer fantastic beits. Superchargers do the same. Depending on what your goals are one will and cam outside the other.

So your superior and better comments are wrong because it’s not true. They both have a place and can both outperform each other at times. No one is flat out better then the other. So making a diffinitive… statement is wrong

#10

There has to be at least someone on this forum besides me who knows enough about this to understand how ridiculius this notion of compressor maps is here.

Maybe if we were arguing about one type of SC versus the other.

Turbos are essentially centrifugal superchargers driven off the exhaust rather than a belt. It’s the same bloody compressor system.

[quote]Superchargers were such a bad idea audi put them on more models then ever in there line up. So have other company’s.
[/quote]
I’ll refrain from being a grammar nazi as it would be off topic and below the belt but wow, man…

Audi have ONE supercharged engine and it’s on its last legs. New one is back to turbo. Like the new 4.0TT.

Like I said

BMW: turbo
Merc: turbo
Ferrari: turbo
Porsche: turbo (even the 991.2 Carrera will be)

Sure Chevy strapped a supercharger onto a ridiculously large engine to make about the same horsepower per litre as our NA 4.2s do. Whoopdie doo.

I never said superchargers don’t have a right to exist either. In fact for the RS4 they are the obvious choice for reasons I listed. But they are inherently less efficient than turbos. Fact of life. And there are cutting edge turbo applications out there that are not laggy at all and offer a fatter wider torque band than you could get by supercharging. Not applicable to the RS4 or the turbo kit/scam.

#11

Sorry man when none of your “facts” are actually facts there’s no sense it talking more about it. Your putting your thoughts in the place as “facts”

Again in some cases supercharged apps will out perform turbos. Sorry you don’t understand compressor maps enough to start with that.

#12

Is “compressor map” all you’ve ever heard of?

You still seem to think they’re relevant for some reason or other even after I’ve told you why they’re not.

You could use the exact same compressor wheel on a SC and a turbo and the setup would perform very differently. With identical “compressor maps”.

So no, there is no answer that could possibly be found in compressor maps. The difference between a turbo and SC lies entirely on the other side of the shaft the compressor wheel sits on.

Anyway, there are a bazillion different compressors to choose from on the turbo side and on the SC side you’d need to choose between very different types of compressors. (e.g. roots or centrifugal) There could never be a universal difference to spot.

#13

JC what continues to amaze me is just how ignorant you really are. In what case can you put the same wheel from a turbo on a supercharger and in that case they would still share the same VE. . None really but that’s fine we know your not automotive smart. But that’s what we’re at AR for to help.

So since you don’t understand this here is my help.

First off anything that compresses air will have a compressor map. So the Germans call the roots style supercharger a kompressor…so moving on. Look at the maps. I know your probably don’t know how because your just like the rest of the uneducated Internet that posts thoughts as facts so I’ll help.

Looking at roots and c fuge maps you will see they carry a higher VE then conventional
Turbo maps. Turbos can get into the low to mid 70s in VE but there range of CFM and speeds at that point are limited. While the Cfuge or roots style carry a VE in some ranges in the 80% VE. If you knew what you were talking about you would have known this.

Also let’s hit the obvious.

It takes 2 turbos to do the work of 1 supercharger… win supercharger.
Sure you can use one big turbo but the lag and efficiency will be terrible.

You can run boost at super low loads and tailor a boost curve of all supercharger apps getting close to 80+% efficiency. That’s not possible with turbos. Again I know you don’t know this but you can tailor a boost curve on a supercharger by adjusting the step up ratio. So with a supercharger you can litterly…male boost positive CFM off idle and do it all the way to red line. Win again supercharger

I can hold your hand more and spoon feed you more answers but it’s a waste because your probably don’t understand this.

You actually posted about parasitic losses and said turbos were better because they recycled exhaust energy. Hey genius did you know to recycle exhaust energy you need to create a restriction and to get that restricted path costs you a ton of energy and you loose even more VE. Probably not.

I’ll say it again. Turbos are great and so are Superchargers. In some cases one will out shine the other. They each have a great impact. Over the years Superchargers have made big strides in efficiency and power not to say turbos haven’t but when you ACTUALLY READ A COMPRESSOR MAP for each you can see supercharged apps offer a much larger range for VE. So while the compressor map isn’t going to be the entire story it will be the start of the story. Since you don’t know that you don’t even know what your talking about.

#14

Another thing to consider… Adding a supercharger to a car that was not previously designed for it typically increases main bearing load and almost always results in a shorter engine life. This is obviously mitigated somewhat by selecting an appropriate target power level for the given powerplant (I think JHM has taken this into consideration). Even most (maybe all? - at least all I have seen) OEM supercharged setups include some kind of additional bracing for the crankshaft to help compensate for the load.

Turbos have their own challenges and design considerations but this is one area where I prefer Turbo over superchargers.

#15

This can be possible yes. But it can be completely eliminated by using an isolated tension system. Much like on the factory S4 and likes the Jhm unit has.

#16

Great posts, Justin. I’m enjoying the debate.

#17

Sadly it can’t even be a debate. I keep trying to be nice but when someone doesn’t even get the most primitive basic starting point. And then says it’s I that don’t get it. It just turned into a hey dumb ass post. I don’t think JV…understood anything that compresses air has a compressor chart for VE and if he actually looked he would see supercharged VE rates are higher and cover a extremely large area in comparison to turbos. Superchargers can run in the 80% VE range turbos can’t. Also in supercharged apps consideration of draw to draw is constant. It’s delivery system is the crank. Turbo apps don’t but put the calculation in like you had perfect manifolds.

I was trying to be nice but when this was said

That’s wrong. And hey just look at a compressor map and you can see that. I went back and read where in nicely said that several times. Not only are turbos not more efficient they are not more salable per unit per VE. You can take 1 supercharger that can flow 1000 CFM and scale your CFM to just about whatever rpm you want. Just adjust the step up ratio and pulley. Sure you can strap on a turbo that makes 1000 CFM but it will be huge and if you want it to actually flow 1000 CFM it will take a good amount of time to spool. You can kill the AR ratio on the turbo to make more CFM down low but then it will never make 1000 CFM because it will choke up top

. And if the turbos were so great why did audi pass them over in favor for the supercharged unit for the S4. the fastest S4 to date keeping the majority of its OEM parts. If were talking scale. You can scale a b8 S4 into the 11s on the stock head unit. That’s not possible with the b5 turbos.

They each have a good place in making power. They both have pints where they shine. Understanding this helps make for a better understanding

#18

Interesting. I guess I don’t knows what this is.

#19

Have you ever taken part in any Dunning-Kruger research?

[quote]In what case can you put the same wheel from a turbo on a supercharger and in that case they would still share the same VE
[/quote]
What VE? Volumetric efficiency? That’s not actually a metric that is normally used for compressors. Engines or anything else with pistons, sure. Compressor blades…not really.

[quote]Looking at roots and c fuge maps you will see they carry a higher VE then conventional
Turbo maps. Turbos can get into the low to mid 70s in VE but there range of CFM and speeds at that point are limited. While the Cfuge or roots style carry a VE in some ranges in the 80% VE. If you knew what you were talking about you would have known this.
[/quote]
The efficiency of compressors is not measured in VE. Not at all.

Before you try to educate anyone you really should know what you’re talking about.

And compressor maps apply to the compressor itself only. Not to the unit (unit being the turbocharger or supercharger)

There is no inherent difference between compressor maps for centrifugal compressors whether they are mounted on a turbo or supercharger so your initial point (which you are straying away from slowly but surely) that the “clue” to what is the difference between SC and TC is invalid

Just for reference a Vortech map vs a Garrett map. There’s more efficiency lines on the latter but that doesn’t really matter.

http://www.greenringer.net/shoot/maps.jpg

So your point was?

[quote]It takes 2 turbos to do the work of 1 supercharger… win supercharger.
Sure you can use one big turbo but the lag and efficiency will be terrible.
[/quote]
If you’re talking about V engines then it is more convenient to use one turbocharger per bank, yes. Not really the point of the argument though is it. A single turbo is not more laggy or less efficient, au contraire, it would get twice the exhaust flow of 2 small ones but manifold design and space requirements favour the twin setup on V engines.

[quote]You can run boost at super low loads and tailor a boost curve of all supercharger apps getting close to 80+% efficiency.
[/quote]
And then you add parasitic loss to it. Compressor efficiency (which rarely if ever hits 80 percent by the way) is one small part of a larger equation. Superchargers have a lot of parasitic loss and turbochargers do not.

[quote]Hey genius did you know to recycle exhaust energy you need to create a restriction and to get that restricted path costs you a ton of energy and you loose even more VE.
[/quote]
Yes but the overall loss is a lot less than superchargers. Automotive knowledge 101 really. Overall efficiency turbochargers are simply better and to argue this point is like arguing the sky is green.

[quote]when you ACTUALLY READ A COMPRESSOR MAP for each you can see supercharged apps offer a much larger range for VE. So while the compressor map isn’t going to be the entire story it will be the start of the story. Since you don’t know that you don’t even know what your talking about.
[/quote]

  1. The efficiency lines on compressor maps are not VE. There is no frigging VE on a compressor map. Capiche?
  2. The compressor itself on a SC or turbo has similar efficiency and mid-70s are about as good as it gets.
  3. At the same boost level the VE of the ENGINE is better with a supercharger but this is offset by large parasitic losses.
  4. the last line applies entirely to yourself as I have just demonstrated.

Stay tuned as next week I might be on the side of the argument that intake manifold spacers are a complete waste of money.

#20

Without wishing to detract from the hilarity of the RS4TT fail, you know as well as anyone that comparing numbers from completely different dynos is not really possible with any degree of accuracy.

The power gain vs intake manifold pressure is probably way off here because didn’t they have the MAF in the hot side piping? If he’s losing air out of the IC the MAF will be measuring a LOT of air that never makes it into the engine. AFR and timing would be pretty far off.

Not sure if they realized that themselves. I would hesitate to do pulls at all with that big of an issue.